Synthesis of energetic polyester thermoplastic homopolymers and energetic thermoplastic elastomers formed therefrom

ABSTRACT

Polymerization of α-bromomethyl-α-methyl-β-propiolactone (BMMPL) or α-chloromethyl-α-methyl-β-propiolactone (CMMPL) yielded thermoplastic homopolymers that upon azidation led to a novel energetic thermoplastic polyester: poly(α-azidomethyl-α-methyl-β-propiolactone) (PAMMPL). An energetic copolyether-ester thermoplastic elastomer was prepared by using glycidyl azide polymer, a dihydroxyl terminated energetic polymer, as a macroinitiator for the polymerization of BMMPL or CMMPL. The azidation of the resulting copolyether-ester yielded an energetic thermoplastic elastomer that melted at between 80° C. and 85° C. Polymerization of α-dibromomethyl-β-propiolactone (DBMPL) resulted in a polymer which upon azidation yielded a new energetic polymer that can be used as a binder or into an energetic thermoplastic elastomer synthesis.

[0001] This application is a continuation-in-part application of U.S.Ser. No. 09/770,380 filed Jan. 29, 2001, now allowed.

FIELD OF THE INVENTION

[0002] The present invention relates to energetic polyesterthermoplastic homopolymers and more particularly to the synthesisthereof and to energetic copolyether-ester thermoplastic elastomersobtained therefrom.

BACKGROUND OF THE INVENTION

[0003] High-energy solid compositions such as propellants and compositeexplosives are usually prepared by combining a variety of materialsincluding oxidizers, binders, plasticizers and a curing agent. Manyenergetic binders are available for use in the preparation of thesehigh-energy compositions. Usually, these binders are obtained by acuring reaction involving the use of isocyanates and polyhydroxylenergetic or non energetic prepolymers. The binders give the insensitivecharacter to high energy compositions. For composite explosives, the useof these binders leads to plastic bounded explosives (PBXs), which arechemically crosslinked and not recyclable. Moreover, the existing meltcast facilities are not suitable for cast-cured PBX. An elegant way toformulate PBXs in available melt cast facilities is to use thermoplasticelastomers. Moreover, an advantage of using thermoplastic elastomers isthat they lead to recyclable PBXs. Furthermore, it would be moredesirable to use energetic thermoplastic elastomers because replacingexplosives by energetic binders in the composition results in a lesserloss of energy in comparison with non energetic binders. The limitationof this technology is that thermoplastic elastomers melting in the rangeof between 80° C. and 100° C. are needed in order to be processed in theexisting melt-cast facilities and that those melting at highertemperatures are not suitable for this process. For years, researchershave tried to synthesize energetic thermoplastic elastomers meltingbetween 80° C. and 100° C. In U.S. Pat. No. 4,707,540, issued to Manser,in 1987, it was established that the polymerization of numerous oxetanemonomers yielded energetic homopolymers that could be used as binders.Among these oxetane polymers, Manser isolated BAMO, an energeticthermoplastic homopolymer which melts at 83° C. Until now BAMO was theonly available energetic thermoplastic homopolymer.

[0004] U.S. Pat. No. 4,806,613, issued to Wardle, in 1989, showed thatenergetic thermoplastic elastomers could be prepared directly in themixer by block polymerization of BAMO with other oxetane polymers.

[0005] Wardle also showed in U.S. Pat. No. 4,952,644, that ABA triblocksor star thermoplastic elastomers could be obtained by polymerization ofthe BAMO monomers with other oxetanes monomers. Although useful, allthese energetic thermoplastic elastomers must comprise BAMO as the hardsegment. Since energetic thermoplastic elastomers are potential productsto introduce in and prepare insensitive high-energy compositions, thereis a need to develop new energetic thermoplastic homopolymers andenergetic thermoplastic elastomers.

SUMMARY OF THE INVENTION

[0006] An object of one embodiment of the present invention is toprovide the synthesis of novel energetic polyester thermoplastichomopolymers by the polymerization ofα-bromomethyl-α-methyl-β-propiolactone (BMMPL) orα-chloromethyl-α-methyl-β-propiolactone (CMMPL) to yield thermoplastichomopolymers which upon azidation, lead to a novel energeticthermoplastic polyester: poly(α-azidomethyl-α-methyl-β-propiolactone)(PAMMPL).

[0007] A further object of the embodiment of the present invention is anenergetic thermoplastic polyester of the formula:

[0008] where n is 4 to 1500. This new energetic polyester melts at 80°C. and can be used as the hard block of an energetic thermoplasticelastomer.

[0009] Another object of this invention is to provide a process tosynthesize energetic copolyether-ester thermoplastic elastomers andparticularly those copolyether-esters that are obtained by usingenergetic dihydroxyl terminated prepolymers such as glycidyl azidepolymer as macroinitiators for the polymerization ofα-bromomethyl-α-methyl-β-propiolactone (BMMPL) orα-chloromethyl-α-methyl-β-propiolactone (CMMPL) followed by theazidation of the resulting copolymers. The resulting copolyether-estersare energetic thermoplastic elastomers, which melt at 80° C.

[0010] Another object of the present invention is also to provide thesynthesis of a novel energetic polyester homopolymer by thepolymerization of α-dibromomethyl-β-propiolactone (DBMPL) to yield anhomopolymer which upon azidation, led to a novel energetic polyester:poly(α-diazidomethyl-β-propiolactone) (PDAMPL). This new energeticpolyester can be used as a binder or be introduced in an energeticthermoplastic elastomer synthesis.

[0011] Where n could be 3 to 1100 leading to molecular weights between500 to 200 000 g/mol.

[0012] In accordance with another feature of the present invention,there is provided a process for preparing an energetic copolyether-esterthermoplastic elastomer of type ABA. This process comprises the step ofusing an energetic dihydroxyl terminated polymer as a macroinitiator topolymerize α-bromomethyl-α-methyl-β-propiolactone (BMMPL) orα-chloromethyl-α-methyl-β-propiolactone (CMMPL) followed by theazidation of the resulting copolymer. The structure of the resultingcopolyether-ester can be illustrated as followed:

PAMMPL-DHTEP-PAMMPL

[0013] where PAMMPL is the hard polyester block A and DHTEP is thedihydroxyl terminated polyether used as the soft block B. Preferably,the dihydroxyl terminated energetic polymer (soft segment) has amolecular weight ranging from about 500 to about 100,000 g/mol and thePAMMPL (hard segment) has a molecular weight of 500 to 200,000 g/mol.Preferably, the dihydroxyl terminated prepolymer is glycidyl azidepolymer (GAP), but is not limited to and could be applied to otherhydroxyl terminated energetic prepolymer selected from the groupconsisting of: poly 3-azidomethyl-3-methyloxetane (AMMO), poly3-nitratomethyl-3-methyloxetane (NIMMO) and poly glycidyl nitrate(GLYN).

[0014] Those skilled in the art will see that the functionality of thesoft segment is not restricted to two. In fact, using the process with adifunctional soft segment resulted in an ABA triblock copolymer butusing a monofunctional soft segment would have resulted in an AB diblockcopolymer. The use of a trio, tetra- or polyfunctional soft segmentwould have led to star shaped or grafted thermoplastic elastomers.

[0015] Yet another object of one embodiment of the present invention isto provide an energetic for use as a prepolymer for binder orthermoplastic elastomer synthesis having the formula:

[0016] Where n could be 3 to 1100 leading to molecular weights between500 to 200 000 g/mol which can be used as a binder or be introduced inan energetic thermoplastic elastomer synthesis.

[0017] Having thus generally denoted the invention, reference will nowbe made to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1 is a schematic illustration of a reaction sequence forforming BMMPL;

[0019]FIG. 2 is a schematic illustration of a reaction sequence forforming GAP-co-PAMMPL; and

[0020]FIG. 3 is a schematic illustration of a reaction sequence forforming DBMPL.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0021] Thermoplastic elastomers (TPE) are copolymers of the typetriblock ABA, diblock AB or multiblock (AB)_(n) where A and B are thehard and soft segments, respectively. Star shaped and grafted copolymersthat include A and B blocks are also thermoplastic elastomers. The hardsegment is capable of crystallization or association and gives thethermoplastic behavior to the copolymer, whereas the soft segment givesthe elastomeric behavior to the copolymer. In practice, at roomtemperature, a thermoplastic elastomer behaves like a rubber because itis crosslinked in the same fashion as a conventional elastomer, but withreversible physical crosslinks. Since the physical crosslinks arereversible, the thermoplastic elastomer can be melted or dissolved in asolvent, so that the polymer can be mixed with other components of, forexample, a melt cast explosive. A gun or rocket propellant or acomposite explosive could be isolated upon cooling or evaporating thesolvent. Cooling or evaporating the solvent lets the broken physicalcrosslinks reform and the elastomeric properties are recovered.Therefore, obsolete material can be melted or dissolved before theseparation of the components leading to a recyclable material. Themolecular weight of the soft segment and the hard segment must bebalanced to get good mechanical properties. Since it is very difficultto predict the mechanical properties of the thermoplastic elastomer, itis often challenging to find the perfect balance for the molecularweights of both segments.

[0022] In the present invention, the novel energetic thermoplasticpolyester was synthesized by polymerizingα-bromomethyl-α-methyl-β-propiolactone (BMMPL) orα-chloromethyl-αmethyl-β-propiolactone (CMMPL) to isolatepoly(α-bromomethyl-α-methyl-β-propiolactone) (PBMMPL) orpoly(α-chloromethyl-α-methyl-β-propiolactone) (PCMMPL).

[0023] The azidation of PBMMPL or PCMMPL in dimethylformamide at 90° C.and 120° C., respectively yieldedpoly(α-azidomethyl-α-methyl-β-propiolactone) (PAMMPL). All the attemptsto do azidation of the BMMPL or CMMPL monomers failed and resulted inthe polymerization of the lactones. Sodium azide as a nucleophileinitiated the polymerization and poor yields were observed. Manyinitiators are suitable for the polymerization of β-propiolactones.

[0024] Cationic initiators usually lead to low molecular weightpolymers. Suitable examples of cationic initiators include, Lewis acids,trifluoroacetic acid, acetyl perchlorate, trifluoroaceticanhydride/aluminum trichloride, boron trifluoride and its derivatives,halonium salts (dialkylbromonium hexafluoroantimonate, etc),trifluoromethanesulfonic acid, methyl triflate, inter alia. Highmolecular weight polymers can be obtained with the use of anionic ororganometallic compounds.

[0025] Suitable anionic initiators useful for the polymerization oflactones include, tertiary amines (triethylamine, pyridine and itsderivatives, etc.), betaines, phosphines (trialkyl or triaryl phophines,etc), sulfides, sodium or potassium, sulfonium salts, ammonium salts,(tetraalkylammonium hydroxides, etc.) carboxylates salts (potassiumbenzoate, tetraalkylammonium acetates, etc), alkoxides (potassiummethoxide, lithium t-butoxide, magnesium ethoxide, etc.), hydroxides(potassium hydroxide and other alkali metal hydroxides), alkyl salts(butyllithium and other alkali metal salts, etc.) inter alia.

[0026] Organometallic initiators formed to be useful include, aluminumderivatives (trialkylaluminum, halogenated derivatives of alkylaluminumor aluminum, aluminum or alkylaluminum alkoxides, aluminum porphyrins,etc.), zinc derivatives (dialkylzinc, zinc or alkylzinc alkoxides,halogenated derivatives of zinc or alkylzinc, etc.) tin derivatives(alkyltin or tin alkoxides, tin 2-ethylhexanoate, dialkyltin oxides,halogenated derivatives of alkyltin or tin, distannoxanes, tin (II)oxide, etc), titanium derivatives (titanium alkoxides, etc), zirconiumderivatives (zirconium alkoxides, etc.), nickel derivatives (nickelcarboxylate, etc.), cadmium derivatives (dialkyl cadmium, etc.), yttriumderivatives (yttrium alkoxides, etc.).

[0027] Organometallic initiators are often used with small amounts ofco-initiators, including water, polyhydroxylated compounds (ethyleneglycol, butanediol, pentaerythritol, etc.), complexing agents (diethylether, acetylacetone, tetrahydrofuran, etc.), etc. The preferredproportion of catalysts vary generally from between 0.1 and 1 mole ofco-initiator per mole of active group of initiator. The preferredinitiator to monomer ratio is between 0.1 and 25% mol/mol. The presenceof diluents is sometimes desirable. Suitable diluents for thepolymerization of these β-propiolactones are common organic solvents,such as toluene, tetrahydrofuran, dimethylformamide, dimethylsulfoxide,diethyl ether, etc. Lithium t-butoxide was chosen to polymerize bothlactones. Those skilled in the art will know that differentfunctionalities of the polylactones can also be obtained using di, tri-or tetra functional initiators.

[0028] α-bromomethyl-α-methyl-β-propiolactone (BMMPL) andα-chloromethyl-α-methyl-β-propiolactone (CMMPL) have to be synthesizedprior to their polymerization. CMMPL could be synthesized in a one stepsynthesis while BMMPL requires three steps.

[0029] According to FIG. 1, 2,2-dibromomethyl propyl acetate (DBMPAc) isobtained by acetylation and bromation of2-hydroxymethyl-2-methyl-1,3-propanediol (HMP) in a one-pot step. DBMPAcis then oxidized to 2,2-dibromomethyl propionic acid (DBMPA) followed bylactonisation to isolate BMMPL. The same synthetic procedure was appliedto prepare CMMPL, but started with the commercial 2,2-dichloromethylpropionic acid (DCMPA). Since only one step is needed to prepare CMMPLcompared to three for the BMMPL, it would be more appropriate to useonly CMMPL but once its polymerization is done with the macroinitiator,the azidation has to be conducted at 120° C. At this temperature, somedegradation of GAP was observed as well as with the other energeticprepolymers. With PBMMPL, the temperature of azidation was 90° C. anddegradation was not observed.

[0030] To prepare the energetic copolyether-ester thermoplasticelastomer, the dihydroxyl terminated prepolymer must be activated toserve as a macroinitiator. To remove the proton of the hydroxyl groups,many reagents can be used, such as organic and inorganic bases, andorganometallic compounds. Example of suitable reagents includehydroxides (potassium hydroxide and other alkali metal hydroxides,etc.), hydrides (sodium hydride and other alkali metal hydrides, etc.),carbonates (potassium carbonate and other alkali metal carbonates,etc.), alkyl salts (butyllithium and other alkali metal lithium, etc.),carboxylates (potassium acetate and other alkali metal carboxylates,etc.), alkoxides (lithium t-butoxide and other alkali metal alkoxides,etc.), organometallics (aluminum derivatives, zinc derivatives, etc.).

[0031] In this application n-butyl lithium was used to generate thealkoxide ion with GAP. The generated alkoxide ions functioned toinitiate the polymerization of CMMPL or BMMPL. This copolymer was thenreacted with sodium azide to isolate the energetic copolyether-esterthermoplastic elastomer. Different mechanical properties can be obtainedby varying the molecular weights of the soft and hard segments. Soft totough rubber or soft to hard waxes are among the possibilities for theappearance of the copolymer. Commercially available glycidyl azidepolymer of molecular weight 2000 g/mol was used as the macroinitiatorfor the polymerization of BMMPL and CMMPL. Azidation of the resultingcopolymers yielded energetic polyether-ester thermoplastic elastomerillustrated in FIG. 2. To increase the elastomeric behavior of thecopolymer, a higher molecular weight (50 000 g/mol) GAP was synthesizedand used as the macroinitiator. It was observed that more elasticity canbe incorporated, but at the expense of a higher viscosity in the moltenstate. As mentioned supra, balancing the molecular weights of bothsegments can be challenging. It is believed that the best mechanicalproperties are obtained using a soft segment of 10 000 to 20 000 g/moland hard segment of 10 000 to 15 000 g/mol on each side of the softsegment.

[0032] The synthesis of α-dibromomethyl-β-propiolactone (DBMPL) andα-dichloromethyl-β-propiolactone (DCMPL) is similar to the one of BMMPL,except that the starting material was pentaerythritol (see FIG. 3).Three steps are needed to complete each synthesis. The first stepinvolved, in both cases, the simultaneous halogenation and acetylationof pentaerythritol to give 3-bromo-2,2-dibromomethylpropyl acetate or3-chloro-2,2-dichloromethylpropyl acetate, respectively. Those acetatesare then oxidized to 3-bromo-2,2-dibromomethyl propionic acid or3-chloro-2,2-dichloromethyl propionic acid. DBMPL or DCMPL are thenobtained by the cyclisation of the acids.

[0033] Having thus described the invention, reference will now be muchto the examples.

[0034] Preface:

[0035] As used herein

[0036]¹HNMR=proton nuclear magnetic resonance, ¹³CNMR=carbon nuclearmagnetic resonance and s is representation of a singlet, d=doublet,q=quintuplet, m=multiplet

[0037] Chemicals

[0038] GAP M_(n)=2000 g/mol (GAP 2000) was obtained from 3M company,Minnesota, U.S.A. GAP M_(n)=50 000 g/mol was synthesized according to aknown process developed by Vandenberg for the synthesis of a highmolecular weight polyepichlorohydrin (PECH) followed by the azidation ofthis PECH to yield a high molecular weight GAP which was used as amacroinitiator.

EXAMPLE 1 α-bromomethyl-α-methyl-β-propiolactone (BMMPL)

[0039] 1) Preparation of 2,2-dibromomethyl Propyl Acetate (DBMPAc)

[0040] In a round bottom flask, equipped with a condenser and a magneticstirrer, a mixture of hydrogen bromide in acetic acid (30% w/w, 500 mL)and of 2-hydroxymethyl-2-methyl-1,3-propanediol (HMP) (100 g, 0,833 mol)was heated to reflux for 24 hours. The solution was then cooled andtransferred into a separatory funnel. After the addition of cold water(1.2 L), the organic phase was separated and distilled to yield2,2-dibromomethyl propyl acetate. The fraction boiling at 80° C. and 0.5mm Hg was collected to yield 225 g of DBMPAc (0.781 mol, 94%).

[0041]¹HNMR: δ (CDCl₃) ppm: 1.18 (s, 3H,CH₃), 2.09 (s, 3H, CH₃CO), 3.42(s, 4H, CH₂Br), 4.07 (s, 2H, CH₂)

[0042] 2) Preparation of 2,2-dibromomethyl Propionic Acid (DBMPA)

[0043] In a three-neck flask equipped with an addition funnel, a largecondenser, a thermometer and a magnetic stirrer, were introducedconcentrated nitric acid (70%, 400 mL, 1.40 g/mL) and fuming nitric acid(50 mL, 1.52 g/mL). This solution was heated to 90° C. and DBMPAc (100g, 0.347 mol) was added dropwise. The temperature was maintained between80° C. and 90° C. for the duration of the addition. Red fumes evolvedabundantly once approximately a third of the MDBMP was added. Themixture was heated at 80° C. and 90° C. for an additional two hoursafter the end of the addition and was stirred overnight at roomtemperature. It was then poured in 2 L of ice water. The solid wasfiltered, washed with ice water and used without further purificationfor the next step (73 g, 0.28 mol, 81%, Mp: 60-62° C.). The aqueousphase was extracted with chloroform to yield a supplementary 16 g ofDBMPA (0.062 mol) which need to be purified by recrystallization in amixture benzene/petroleum ether to give almost a quantitative yield forthe reaction.

[0044]¹HNMR: δ (CDCl₃) ppm: 1.49 (s, 3H,CH₃), 3.70 (q, 4H, CH₂Br), 10.5(s, COOH).

[0045] 3) Preparation of α-bromomethyl-α-methyl-β-propiolactone (BMMPL)

[0046] In a beaker equipped with a magnetic stirrer, DBMPA (60 g, 0.228mol) was added to water (600 mL). To this suspension was added dropwisea potassium carbonate solution (1.0 M) until the pH of the solution was8 (approximately 180 mL). When all the DBMPA was dissolved, the solutionwas quickly filtered into an Erlenmeyer flash and methylene chloride wasadded (600 mL). This mixture was strongly stirred for 18 hours anddecanted into a separatory funnel. The organic phase was separated andthe aqueous phase was washed with methylene chloride (2×300 mL). Theorganic phases were combined and dried over magnesium sulfate, filteredin a round bottom flask previously washed with hydrochloric acid (1 M)and evaporated to yield BMMPL (36 g, 0.20 mol). This product was rapidlyfiltered again on a neutral alumina column under dynamic vacuum into around bottom flask also washed with HCl 1 M, dried over calcium hydridefor three hours and distilled under vacuum over molecular sieves. Thefraction boiling between 37° C. and 39° C. at 1 mm Hg was collected toyield 27 g (0.15 mol, 65%). This pure BMMPL was stored over molecularsieves and under a nitrogen atmosphere at 5° C.

[0047]¹HNMR: δ (CDCl₃) ppm: 1.59 (s, 3H,CH₃), 3.45, 3.67 (2 d, 2H,CH₂Br), 4.11,4.39(2 d, 2H, CH₂).

[0048]¹³CNMR: δ (CDCl₃) ppm: 19.08 (CH₃), 33.43 (CH₂Br), 58.99 (C) 71.33(CH₂), 171.49 (CO).

EXAMPLE 2 α-chloromethyl-α-methyl-β-propiolactone (CMMPL)

[0049] The synthesis of CMMPL is similar to the synthesis of BMMPL,except that the starting available material was 2,2-dichloromethylpropionic acid (DCMPA) (20 g, 0.12 mol). It was poured into 800 mL ofwater, neutralized to pH 8 with a 1.0 M potassium carbonate solution(approximately 80-90 mL), filtered and vigorously agitated overnightwith 800 mL of chloroform. The fraction boiling between 55° C. and 57°C. at 1 mm Hg was collected to yield 7.6 g (0.054 mol, 45%). This pureCMMPL was stored over molecular sieve and under a nitrogen atmosphere at5° C.

[0050]¹HNMR: δ (CDCl₃) ppm: 1.56 (s, 3H,CH₃), 3.59, 3.81 (2 d, 2H,CH₂C1), 4.12, 4.45 (2 d, 2H, CH₂).

[0051]¹³CNMR: δ (CDCl₃) ppm: 18.22 (CH₃), 45.30 (CH₂Cl), 59.48 (C) 70.11(CH₂), 171.74 (CO).

EXAMPLE 3 Poly(α-bromomethyl-α-methyl-β-propiolactone) (PBMMPL)

[0052] Freshly distilled anhydrous BMMPL (2.21g, 12.3 mmol) was injectedinto a flame-dried two-neck flask equipped with a magnetic stirrer, anitrogen inlet and septa, previously flushed under vacuum and kept undera nitrogen stream. BMMPL was injected with a syringe precisely weighedbefore and after the injection. Anhydrous tetrahydrofuran (THF) (12.0mL) was injected in the flask followed by an injection (496 μL) of asolution of lithium t-butoxide in THF (1.0 mol/L). In less than fiveminutes, the mixture was solid. After 24 hours, this solid was stirredin methanol (80 mL), filtered and dried under vacuum at 60° C. for 24hours. PBMMPL was isolated as a fine white powder (1.56 g, 71%) and wasinsoluble in most organic solvents. DSC analyses revealed a meltingpoint of 230-245° C. followed by decomposition of the polymer and anenthalpy of fusion of between 40 Jules/g and 50 Jules/g. Since thepolyester is insoluble, molecular weight could not be determined.

EXAMPLE 4 Poly(α-chloromethyl-α-methyl-β-propiolactone) (PCMMPL)

[0053] The procedure for the polymerization of CMMPL can be almostidentical to the one for BMMPL, but other catalysts worked as well. Asan example, a 1.0 M solution of triethylaluminium in hexane (2.24 mL,2.24 mmol) and 20 μL (1.11 mmol) of water were injected into aflame-dried two-neck flask equipped with a magnetic stirrer, a nitrogeninlet and septa, previously flushed under vacuum and kept under anitrogen stream. The initiator was then reacted 0.5 h and dried undervacuum 0.5 h. Anhydrous toluene (9 mL) and freshly distilled CMMPL (2.9g, 22 mmol) were added to the two-neck flask. The solution formed a gelvery quickly. After two hours, the polymer was precipitated in a 10% v/vsolution of hydrochloric acid in methanol (100 mL) and washed with puremethanol until neutral, filtered and dried under vacuum at 60° C. for 24h. PCMMPL was isolated as a fine white powder (2.87 g, 99%) and wasinsoluble in most organic solvents. DSC analyses revealed a meltingpoint of between 200° C. and 250° C. followed by decomposition of thepolymer and an enthalpy of fusion of same or provides 60-75 J/g. Sincethe polyester is insoluble, its molecular weight can not be determined.

EXAMPLE 5 Poly(α-azidomethyl-α-methyl-β-propiolactone) (PAMMPL)

[0054] In a three-neck flask equipped with a condenser, a thermometerand a magnetic stirrer, were introduced PBMMPL (7.29 g, 40.7 mmol ofCH₂Br) dimethylformamide (DMF, 88 mL) and sodium azide (2.92 g, 44.9mmol). The suspension was heated to 90° C. for 18 hours and then pouredin a beaker containing water (800 mL) to be stirred vigorously. Thepolymer was isolated by filtration and dried under vacuum at 60° C. for24 hours, yielding 6.66 g of PAMMPL (99%). According to NMRspectroscopy, the azidation was complete. DSC analyses revealed amelting point of 85° C. and an enthalpy of fusion of 35-40 J/g. Sincethe polyester is only partly soluble in common organic solvents, itsmolecular weight could not be determined.

[0055]¹HNMR: δ (DMSO) ppm: 1.1 (s, 3H,CH₃), 3.5 (s, 2H, CH₂N₃), 4.1 (s,2H, CH₂).

[0056]¹³CNMR: δ (DMSO) ppm: 17.7 (CH₃), 46.8 (C), 54.1 (CH₂N₃) 66.3(CH₂), 171.8 (CO).

[0057] The same procedure was applied with PCMMPL except that thetemperature was 120° C. for 24 hours. PAMMPL was isolated as describedwith an overall yield of 71%. The spectroscopic analysis was identical.PAMMPL is a white cotton like solid that had a melting point of 80° C.and an enthalpy of fusion of same or provides 25-30 J/g. The molecularweight could not be determined because of the low solubility of thispolymer in common organic solvents.

EXAMPLE 6 Synthesis of (GAP-2000)-co-PBMMPL Thermoplastic Elastomer

[0058] GAP-2000 (0.316 g, 3.19 mmol of CH₂N₃) was thoroughly driedovernight under vacuum at 50° C. in a three-neck flask equipped with astirrer, a nitrogen inlet and septa. GAP was then put under a nitrogenstream for the remainder of the reaction. Anhydrous tetrahydrofuran (3.2mL) was added to the flask and, after complete dissolution of GAP, a 1.6M solution of n-butyl lithium in hexane (0.164 mL,0.263 mmol) wasinjected, followed by 1.012 g (5.65 mmol) of BMMPL. The material (1.10g, 83%) was recuperated 24 h later by precipitation in methanol,filtration and drying overnight under vacuum at 60° C. DSC analysesindicated a glass transition temperature of −29° C., characteristic ofthe soft segments of GAP. The melting point of the hard segments,expected above 200° C. from the results obtained for PBMMPL, could notbe detected because of the decomposition of GAP beginning at 200° C. Themolecular weight of this material could not be determined because of itsinsolubility in common organic solvents. The copolymer was composed of52% mol/mol GAP, as evaluated by the quantity of nitrogen in the polymerdetermined by elementary analysis (% C=34.5%, % H=4.5% % N=10.7%).

EXAMPLE 7 Synthesis of (GAP 2000)-co-PAMMPL Energetic ThermoplasticElastomer

[0059] In a three-neck flask equipped with a condenser, a thermometerand a magnetic stirrer, were introduced (GAP 2000)-co-PBMMPL (0.204 g),dimetbylformamide (DMF, 4.0 mL) and sodium azide (0.074 g, 1.14 mmol).The suspension was heated to 90° C. for 18 hours and then poured in abeaker containing water to be stirred vigorously. After a few hours ofagitation, the polymer stuck to the walls of the beaker; it was isolatedby decantation of water and dried under vacuum at 60° C. for 24 hours,yielding 0.171 g of PAMMPL-GAP-PAMMPL. DSC analyses revealed a glasstransition temperature of −26° C., a melting point between 80° C. and85° C. and an enthalpy of fusion of 12 Jules/g. The molecular weight wasestimated at 7300 g/mol from GPC measurements.

EXAMPLE 8 Synthesis of GAP-co-PBMMPL Thermoplastic Elastomer

[0060] High molecular weight GAP (162.8 g, 1.64 mol of CH₂N₃) wasthoroughly dried under vacuum at 50° C. for 4-5 days in a 4-L reactionkettle equipped with a mechanical stirrer, a nitrogen inlet and septa.GAP was then put under a nitrogen stream for the remainder of thereaction. Anhydrous tetrahydrofuran (3 L) was added to the reactionkettle and, after complete dissolution of GAP, a 1.6 M solution ofn-butyl lithium in hexane (20.5 mL, 32.9 mmol) was injected, followed by154.5 g (0.863 mol) of BMMPL. The material (270 g, 85%) was recuperated24 h later by precipitation in methanol, filtration and drying undervacuum at 60° C. for 2-3 days. DSC analyses indicated a glass transitiontemperature of-32° C., characteristic of the soft segments of GAP. Themelting point of the hard segments, expected above 200° C. from theresults obtained for PBMMPL, could not be detected because of thedecomposition of GAP beginning at 200° C. The molecular weight of thismaterial could not be determined because of its low solubility in commonorganic solvents.

EXAMPLE 9 Synthesis of GAP-co-PAMMPL Energetic Thermoplastic Elastomer

[0061] In a three-neck flask equipped with a condenser, a thermometerand a magnetic stirrer, were introduced PBMMPL-GAP-PBMMPL (250 g),dimethylformamide (DMF, 5.0 L) and sodium azide (91.0 g, 1.40 mol). Thesuspension was heated to 90° C. for 18 hours and then poured in a beakercontaining water to be stirred vigorously. The polymer was isolated byfiltration and dried under vacuum at 60° C. for 24 hours, yielding 160 gof PAMMPL-GAP-PAMMPL. DSC analyses revealed a glass transitiontemperature of −31° C., a melting point of 86° C. and an enthalpy offusion of 2-3 Jules/g. Since the polyester is only partly soluble incommon organic solvents, its molecular weight could not be determined.

EXAMPLE 10 α-dibromomethyl-β-propiolactone (DBMPL)

[0062] 1) Preparation of 3-bromo-2,2-dibromomethylpropyl Acetate(BDBMPAc)

[0063] This synthesis is similar to the one of DBMPAc, except that 60 gof pentaerythritol (0.45 mol) were reacted with 500 mL of hydrogenbromide in acetic acid (30% w/w). The yield of BDBMPAc after theextraction was 92% (152 g, 0.414 mol). This product can be used in thenext step without additional purification.

[0064]¹HNMR: δ (CDCl₃) ppm: 2.11 (s, 3H,CH₃), 3.54 (s, 6H, CH₂Br), 4.19(s, 2H, CH₂)

[0065] 2) Preparation of 3-bromo-2,2-dibromomethyl Propionic Acid(BDBMPA)

[0066] This synthesis is similar to the one of DBMPA, except that for100 g of BDBMPAc (0.272 mol), 310 mL of concentrated nitric acid (70%,1.40 g/mL) and 36 mL of fuming nitric acid (1.52 g/mL) were needed. Thetotal yield of BDBMPA (MP: 83-86° C.) was 86% (72 g, 0.21 mol).

[0067]¹HNMR: δ (CDCl₃) ppm: 3.77 (s, CH₂Br).

[0068] 3) Preparation of α-dibromomethyl-β-propiolactone (DBMPL)

[0069] This synthesis protocol was similar to that for BMMPL. Yields areof between 60% and 70% were residual distillation (55-59° C., 1 mm Hg).

[0070]¹HNMR: δ (CDCl₃) ppm: 3.79 (s, 4H, CH₂Br), 4.45 (s, 2H, CH₂).

EXAMPLE 11 α-dichloromethyl-β-propiolactone (DCMPL)

[0071] 1) Preparation of 3-chloro-2,2-dichloromethylpropyl Acetate(CDCMPAc)

[0072] This synthesis protocol was similar that for BDBMPAc, except that20 g of pentaerythritol (0.15 mol) were reacted at 160° C. in a closedvessel with 225 mL of hydrochloric acid and 75 mL of glacial aceticacid. After 24 h, the solution was cooled and transferred into aseparatory funnel. After the addition of cold water (300 mL), theorganic phase (14.1 g) was separated. NMR analysis revealed that thisphase was constituted of a mixture of CDCMPAc (84%) and2,2-dichloromethylpropyl acetate (DCMPAc). The rest of the solution wasextracted with methylene chloride, dried and evaporated to yield again amixture (14.6 g) of CDCMPAc (46%) and DCMPAc. CDCMPAc could not becompletely purified by distillation; it was noted that the boilingtemperature rose continuously between 82° C. and 110 C (1 mm Hg). Thefirst fraction (20.1 g), isolated between 82° C. and 102° C., containedapproximately 85% CDCMPAc, while the second one (4.2 g, 103-110° C.) wascomprised of 73% CDCMPAc.

[0073]¹HNMR: δ (CDCl₃) ppm: 2.10 (s, 3H,CH₃), 3.64 (d, 6H, CH₂Cl), 4.16(s, 2H, CH₂)

[0074] 2) Preparation of 3-chloro-2,2-dichloromethyl Propionic Acid(CDCMPA)

[0075] The synthesis protocol was similar to that for DBMPA, except thatfor 24 g of CDCMPAc, 121 mL of concentrated nitric acid (70%, 1.40 g/mL)and 13.6 mL of fuming nitric acid (1.52 g/mL) were needed. The totalyield of CDCMPA was 74% (15.9 g, 0.77 mol).

[0076]¹HNMR: δ (CDCl₃) ppm: 3.87 (s, CH₂Cl).

[0077] 3) Preparation of α-dichloromethyl-β-propiolactone (DCMPL)

[0078] The synthesis protocol similar to that for of BMMPL.

[0079]¹HNMR: δ (CDCl₃) ppm: 3.90 (d, 4H, CH₂Cl), 4.44 (s, 2H, CH₂).

EXAMPLE 12 Poly(α-dibromomethyl-β-propiolactone) (PDBMPL)

[0080] The synthesis protocol was similar to that for PBMMPL and PCMMPL.PDBMPL was found to be a fine white powder which was insoluble in mostcommon organic solvents.

EXAMPLE 13 Poly(α-dichloromethyl-β-propiolactone) (PDCMPL)

[0081] The synthesis protocol was similar to that for PBMMPL and PCMMPL.PDCMPL was found to be a fine white powder which was insoluble in mostcommon organic solvents.

EXAMPLE 14 Poly(α-diazidomethyl-β-propiolactone) (PDAMPL)

[0082] The synthesis is similar to that for PAMMPL, except that for 1.05g of PDBMPL (4.07 mmol), 12.6 mL of dimethylformamide and 0.581 g ofsodium azide (8.9 mmol) were needed. The molecular weight could not bedetermined because of the low solubility of PDAMPL in common organicsolvents.

[0083]¹HNMR: δ (DMSO) ppm: 3.7 (s, 4H, CH₂N₃), 4.2 (s, 2H, CH₂)

We claim:
 1. An energetic copolyether-ester thermoplastic elastomer ofthe formula: PAMMPL-DHTEP-PAMMPL where PAMMPL ispoly(α-azidomethyl-α-methyl-β-propiolactone) and DHTEP is dihydroxylterminated energetic polymer.
 2. The energetic copolyether-esterthermoplastic elastomer as set forth in claim 1, wherein said elastomerhas a melting point of between 80° C. and 85° C.
 3. The energeticcopolyether-ester thermoplastic elastomer as set forth in claim 1,wherein the dihydroxyl terminated energetic polymer is selected from thegroup comprising of glycidyl azide polymer (GAP), poly3-azidomethyl-3-methyloxetane (AMMO), poly3-nitratomethyl-3-methyloxetane (NIMMO) and polyglycidyl nitrate (GLYN).4. The energetic copolyether-ester thermoplastic elastomer as set forthin claim 3, wherein the molecular weight of said soft segment is between500 and 100 000 g/mol and the molecular weight of said hard segmentPAMMPL is between 500 and 200 000 g/mol.
 5. The energeticcopolyether-ester thermoplastic elastomer as set forth in claim 4,wherein the functionality of said soft segment is between 1 and
 250. 6.The energetic copolyether-ester thermoplastic elastomer as set forth inclaim 5, wherein said functionality is two.
 7. A process for preparingan energetic copolyether-ester thermoplastic elastomer of the formula:PAMMPL-DHTEP-PAMMPL where PAMMPL ispoly(α-azidomethyl-α-methyl-β-propiolactone) and DHTEP is dihydroxylterminated energetic polymer, comprising: providing a dihydroxylterminated telechelic energetic polymer having a functionality of two;polymerizing BMMPL or CMMPL with said energetic to form a copolymer; andaziding said copolymer.
 8. The process as set forth in claim 7, whereinsaid copolymer has a melting point of between 80° C. and 85° C.
 9. Theprocess as set forth in claim 7, wherein said dihydroxyl terminatedpolyether is a soft segment having a molecular weight between 500 and200,000 g/mol.
 10. The process as set forth in claim 7, wherein saidPAMMPL is a hard segment having a molecular weight between 500 and200,00 g/mol.
 11. The process as set forth in claim 10, wherein saiddihydroxyl terminated polymer is selected from the group comprising:3-azidomethyl-3-methyoxetane (AMMO), poly 3-nitratomethyl-3methyloxetane (NIMMO), poly glycidyl nitrate (GLYN) and glycidyl azidepolymer (GAP).
 12. An energetic for use as a prepolymer for binder orthermoplastic elastomer synthesis having the formula:


13. The energetic polyester as set forth in claim 12, wherein n isbetween 3 to
 1100. 14. The energetic polyester as set forth in claim 13,wherein said polyester has a molecular weight of 500 g/mol when n is 3.15. The energetic polyester as set forth in claim 13, wherein saidpolyester has a molecular weight of 200,000 g/mol when n is
 1100. 16. Aprocess for preparing an energetic polyester as in claim 3, comprisingthe step of polymerizing DCMPL or DBMPL followed by the azidation of theresulting PDCMPL or PDBMPL.